Subarachnoid Hemorrhage


Subarachnoid hemorrahge CT scan

Figure 1. CT scan of head, read as normal in ED.

Subarachnoid hemorrahge CT scan

Figure 2. Additional CT cut

Subarachnoid hemorrahge CT scan

Figure 3. CT showing subarachnoid blood to right of brainstem.

A 35-year-old Asian man presents to the emergency department with a severe headache. He states he rarely gets headaches, but has been having them on and off all week, all mild to moderate until tonight, when right after sexual intercourse, he experienced a sudden severe headache and vomited twice. He denies having had any fever, neck stiffness, or changes in strength, coordination, speech, or vision and has no other complaints.

He denies any past medical history or drug use. There is no family history of aneurysm or migraine but his mother is a dialysis patient.

On examination his vital signs are normal and he appears to be in mild distress. You think his neck may be a little stiff, but he can bend his chin to his chest. The rest of his examination, including a full neurologic examination, is normal.

Labs are normal except for a sodium level of 132 mEq/L and a creatinine of 1.6 mg/dL. A CT scan of the brain is ordered and read by the radiologist as normal (Figure 1); you then recommend a lumbar puncture (LP), but the patient refuses despite all the terrible things you tell him may happen if he has an aneurysm or meningitis. He goes on to state that he has been using his smart phone to research headaches and thinks he has a “post-coital headache,” which he read is not dangerous.

What should you do next?  

Should you call in a consult? Who?

Answer: Call neurosurgery

Hyponatremia can cause headache but it would not be of abrupt onset; it can also cause nausea although the sodium level would more likely be less than 130 mEq/L. The family history of renal failure, with or without the patient’s current creatinine level of 1.6 mg/dL, should prompt you to ask about polycystic kidney disease-a hereditary condition that is also a risk factor for cerebral aneurysms. A LP is actually not necessary because on close inspection, the CT scan actually shows a small subarachnoid hemorrhage. Additional cuts of the CT are shown (Figures 2 and 3) with an arrow (Figure 3) pointing to subarachnoid blood on the right side of the brainstem. The blood resembled an extension of the tentorium, which was probably why it was missed by the radiologist on the preliminary read.

If the CT scan had been negative, you would call his mother, his spouse, significant other, or primary care physician to help convince him to undergo LP. Another helpful technique to address patient fear of undergoing LP is to explain that the procedure is very similar to having epidural anesthesia or “an epidural” and about 80% of women in the United States are given an epidural when giving birth.

The patient was admitted to the ICU with standard treatment for a subarachnoid hemorrhage. Interestingly his MRA and regular angiogram were both negative. Evidently this occurs in about 15% of documented subarachnoid bleeds, so his smart phone got lucky.


Subarachnoid hemorrhage is a rare but potentially fatal condition. Symptoms typically include a severe headache that peaks suddenly or within minutes of onset and is different from prior headaches. Additional historical features can include onset with exertion or sex, occipital location of pain, neck stiffness, syncope or bucking of legs, and vomiting. In severe cases the patient will have altered mental status or be comatose. Risk factors include polycystic kidneys and Ehlers-Danlos syndrome but also hypertension, lupus, and alcohol or tobacco abuse. Physical examination may be normal or may show neck stiffness.

Imaging issues

Results of the head CT scan will be positive in the vast majority of cases, especially if the test is performed within 6 hours of headache onset in a patient with no history of anemia. Traditionally, if the CT scan is negative and there is significant suspicion, a LP should be performed to definitively rule out subarachnoid hemorrhage. Recent data, however, suggest this may not be necessary when the CT is performed within 6 hours of headache onset and there is no anemia. More than 100 red blood cells/mL in the final tube of cerebrospinal fluid or the presence of xanthochromia warrant neurosurgical consultation followed by a cerebral angiogram. MR or CT angiogram can be considered if LP is refused or contraindicated, but positive results on these advanced imaging tests can be problematic as 2% to 4% of the US population have asymptomatic aneurysms that do not require treatment if they are not leaking.  CT or MR angiogram should also be considered if there is clinical concern for carotid or vertebral dissection or if there are significant findings on neurologic examination.

Initial stabilization of the patient with a subarachnoid hemorrhage typically involves analgesia, supportive care, and nimodipine and/or nicardipine if blood pressure is higher than 150/80 mm Hg. Definitive care is aneurysm occlusion either by operative repair and clipping or by endovascular placement of various materials to occlude the aneurysm from within. See Table for more details.


Incidence: 1 in 30,000
Sudden, peaks within 5 mins; not like prior headaches. "Acute & atypical"
Red flags:
911-call, vomiting, onset w/ exertion, age>40, BP>160/100 mm Hg, occipital, neck pain/stiffness Syncope, injury, BP high, ECG changes, tinnitus, vomiting, legs buckle
Resolves on own or w/ non-opiate meds, not worst HA of life, neck pain only, recurrent HA
Asian, polycystic kidneys, Ehlers-Danlos, lupus, smoking, heavy alcohol, HTN
False negs:
CT: small bleed, hematocrit <30, headache >6 hours, AVM. LP: <4 hours or >2 weeks, xanthochromia: 50% sensitive only
Not as sensitive (85%) or specific (2-4% of people have asymptomatic aneurysms) as LP.
Dissection, LP refused/contraindicated, PCKD, Marfan, diplopia, seizure, focal exam
Call neurosurgery, nimodipine 60mg PO q4, nicardipine IV if BP>150/80 mm Hg


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